IF THE THUGS in the Oakdale Mob are not deterred by the prospect of long prison sentences for murder and drug dealing -- among their many alleged crimes -- why would they give a moment's thought to a court injunction to stop them from hanging out in a four-block section of Bayview-Hunters Point?

In truth, a few days in jail or $1,000 fines are unlikely to instill much fear in a notorious gang that has run amok in the neighborhood for far too long. Members of the gangs are suspected in at least 12 killings over the past three years.

Nevertheless, City Attorney Dennis Herrera's office will try to persuade a Superior Court judge today to issue a preliminary injunction to keep 22 of the core gang members from congregating in the area around Oakdale Avenue and Baldwin Court near public housing in the southeast corner of San Francisco.

Any government attempt to curtail free association should be subject to close scrutiny. In this case, Herrera has more than 1,000 pages of documentation of the Oakdale Mob's reign of terror. He also narrowed the designated "safety zone" -- where the targeted gang members could still come and go, but with restrictions on their activities -- to the four-block area. Other cities, such as Los Angeles, have secured injunctions restricting the actions of gang members over much wider swaths of the city.

District Attorney Kamala Harris, who supports Herrera's move, acknowledged that "the best way to get those guys is to convict them and send them to prison." Still, she suggested the civil and criminal penalties could serve to unnerve the gang with the "threat of something that is ominous and unknown." Equally significant is the signal that it sends to law-abiding residents who have been intimidated by the gangsters and are wary of the city's inability to stop the violence.

The understandable reluctance of residents to cooperate with investigations is a long-running impediment to cracking down on the Oakdale Mob. The injunction should encourage more communication between the neighborhood and police. If it is enforced with consistency and reasonableness, it will help establish a trust that has been missing.